Concrete sealing: what to know

What the job involves, what changes the price, and what to ask a pro.

What concrete sealing is

Concrete sealing puts a protective layer on a slab to resist water, stains, salt and oil. Driveways, patios and garage floors are the most common surfaces, and the right sealer depends on whether the concrete is new, old, smooth or textured and what it will face.

Signs you need it

  • Water soaks into the surface and does not bead up, or the slab darkens after rain
  • Oil and fluid stains from cars and equipment set into the concrete and will not wash out
  • Salt and de-icing products have left the surface scaling or chalky in winter
  • A new slab has cured and needs protection before its first season of use
  • The garage floor dusts or takes on stains from tires and spills, and needs a tougher surface
  • The old sealer is peeling, wearing thin or turning cloudy, and the slab looks worn in traffic areas

What the pro does

  • Test the surface for moisture and check whether any old sealer is present, since the test decides the product choice
  • Clean the slab with a degreaser and a pressure washer, then remove any old sealer that is failing
  • Repair small cracks and spalls so water does not get under the new coat
  • Apply a penetrating sealer by sprayer or roller in even passes, or a film-forming sealer in thin coats if the look needs it
  • Back-roll or squeegee the surface as directed so the sealer soaks in evenly and does not pool
  • Keep traffic off the surface until the sealer has cured, then explain the reseal interval and the cleaning to use

What changes the price

Every job is different, so we do not publish prices. These are the things that move the quote up or down.

  • Total area and whether the surface is a driveway, patio, garage floor or pool deck
  • Condition of the slab, since heavy staining, old peeling sealer or oil spots take more cleaning and prep
  • The type of sealer, such as penetrating or film-forming, and whether it is a slip-resistant or high-gloss finish
  • Number of coats and whether the work is one pass or needs extra passes on thirsty or porous concrete
  • Access and timing, since the surface must be dry and the weather must stay mild through the cure
  • Whether the surface needs repairs, grinding or a degreasing step before the sealer can go on

What a written quote should spell out

  • Area to be sealed and the surface type, such as broom finish, stamped or exposed aggregate
  • Cleaning method and whether oil or stain treatment is included
  • Sealer type, brand or product name, the number of coats and the application method
  • Crack or spall repair, listed separately if it is needed before sealing
  • Cure time and when vehicles and foot traffic can return to the surface
  • Reseal interval recommended for the sealer and the surface use

Questions to ask before you hire

  • Which sealer do you recommend for my surface, and why is it better than the others?
  • Will the sealer change the color or make the surface shiny or slippery?
  • How do you test whether the slab is ready for sealing?
  • How do you remove old sealer, and what do you use for oil stains?
  • How long do I have to keep cars off the surface after sealing?
  • How often should I reseal, and what do I use to clean the surface in between?

Red flags

  • Applies a film sealer over a slab that has moisture or old peeling sealer on it
  • Says one sealer works on every surface without testing the concrete
  • Sprays sealer on a wet or freshly rained-on surface
  • Promises the sealer will stop all cracking and staining for good
  • Skips the cleaning step and seals over oil and grime

What you can do yourself

A homeowner can clean a driveway or patio with a degreaser and pressure washer, and can apply a penetrating sealer on a small, dry, clean surface. Call a pro for garage floors with heavy oil stains, old failing sealers that need removal or grinding, large areas, or any surface that must be slip-resistant for a pool or stairs. Sealers and degreasers release fumes and can irritate skin and eyes, so use gloves, eye protection and good airflow.

Licenses and permits

Whether concrete sealing needs a contractor license varies by place and by how the job is billed. Check with your state or local licensing agency before hiring someone for a large job, and ask your local building department if a permit ever applies.

Concrete sealing questions

Will a sealer make my driveway slippery?

Some sealers, especially high-gloss film types, can become slick when wet. Ask for a slip-resistant option or a penetrating sealer if traction matters on your surface.

How long does a sealer last?

It depends on the product, the traffic, the sun exposure and how often the surface is cleaned, so ask the pro for the reseal interval for your sealer. Surfaces that take heavy traffic or salt will need resealing sooner.

Can I seal a new slab right away?

No, new concrete needs time to cure and to dry out before a sealer can soak in properly. Ask the pro to test for moisture and to confirm the cure time before applying the sealer.

About this guide

This national guide is written and checked by infinibell. Rules and conditions differ by place, so local pros are credited on guides for the cities they serve, not on national ones.

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